Chapter 2. Spitzer History and Mission Overview

2.1 History and Organization of the Spitzer Project

The Spitzer Space Telescope began life as the Shuttle Infrared Telescope Facility (SIRTF) at the NASA Ames Research Center in 1971. The early history and subsequent development are described in detail by G. Rieke (2006, “The Last of the Great Observatories,” Univ. Arizona Press) and by M. Werner et al. (2004, ApJS, 154,1). Key milestones in this history are:

June 1984 Selection of SIRTF instrument teams and Science Working Group.

1988 Decision to implement SIRTF in High Earth Orbit.

January 1990 Transfer of management responsibility for SIRTF from NASA Ames to JPL/Caltech.

November 2000 Selection of the first SIRTF Legacy Science programs – large programs which established new modes of community participation in NASA missions.

August 2003 Launch of SIRTF.

December 2003 Release of first SIRTF data and renaming of SIRTF as the Spitzer Space Telescope, to honor Lyman Spitzer, Jr.

May 2009 Depletion of Spitzer cryogen.

July 2009 Start of Spitzer Warm Mission.

Although it took many years for Spitzer to go from Science Working Group/instrument selection to project start in 1996, the intervening years were not wasted; indeed, during this time the three instrument teams engaged in intensive detector technology development activities, resulting in an ensemble of focal plane arrays which achieved natural-background-limited performance even when used on a cryogenic space telescope. In the final realization, the teams used these arrays in ways which simplified instrument design and reliability. During this same time period, a very effective cryogenic optics development program led to a prototype all-beryllium telescope which was converted to the flight telescope after the selection of the contractor team.

The project organization for the development phase from 1996 to 2003 is shown in Figure 2.1. Ball Aerospace, which built the Cryogenic Telescope Assembly, including the telescope, cryogenic system, and associated shields and shells, was one of two major industrial partners. Ball also built the scan mirror mechanism for MIPS and was the contractor working with Cornell and U. Arizona to build the IRS and MIPS instruments, respectively. The other major industrial partner was Lockheed Martin Sunnyvale, which provided the spacecraft, the solar panel, and the system engineering, integration, and test for the observatory. NASA Goddard Space Flight Center was contracted by Harvard-SAO to build the IRAC instrument. The instrument Principal Investigators and their institutions are listed in Section 2.3 below. Spitzer had no foreign partners during the development phase, although scientists from across the world have applied successfully for observing time on Spitzer during the operations phase.

The launch of Spitzer was followed by two-month in-orbit checkout and one-month science verification phases which were paced by the cooldown of the telescope. Execution of the Spitzer science program began on 1 December 2003, and the first public data release and naming of the observatory occurred later that month. During this time, the project organization was changed to one more appropriate for the operations phase of the mission, as is shown in Figure 2.2. In this transition, Lockheed Martin Sunnyvale was superseded by Lockheed Martin Denver, who took responsibility for spacecraft operations. Ball Aerospace monitored the performance of the cryogenic system and estimated the amount of helium remaining. Day-to-day responsibility for the science instruments was transferred, by pre-agreement, from the instrument teams to the Spitzer Science Center. The Ball Aerospace support ended with the depletion of the helium and the transfer to the Spitzer warm mission. Also at this time, the operational responsibilities of the Spitzer Science Center for the IRS and MIPS instruments terminated since they are not used in the warm mission.

Spitzer is supported within NASA by the Astrophysics Division of what is now called the Science Mission Directorate. Programmatically, Spitzer completes NASA’s family of Great Observatories, which also includes the Hubble Space Telescope, the Chandra X-Ray Observatory, and the Compton Gamma Ray Observatory (recently superseded by the Fermi Gamma Ray Telescope). Like its sister Great Observatories, Spitzer is operated as an observatory for the entire scientific community, with the bulk of the observing time (>80% during the cryogenic mission; 100% during the warm mission) available to the international scientific community through a peer-reviewed time allocation process.

A largely complete list of the many people who worked on the Spitzer project development and thus contributed to the great success of Spitzer is given in Werner et al. (2004) and updated at the end of this document in Appendix C. However, it is appropriate here to single out the four outstanding Project Managers who led the project during development and operations. These are: Larry Simmons who served from 1993 to 1999, David Gallagher (1999-2004), Robert Wilson (2004-2010) and Suzanne Dodd (2010 - ).